Effect of Nanoscale W Coating on Corrosion Behavior of Diamond/Aluminum Composites

At a Glance

Metadata	Details
Publication Date	2023-01-11
Journal	Nanomaterials
Authors	Ping Zhu, Qiang Zhang, Yixiao Xia, Kai Sun, Xiu Lin
Institutions	Harbin Institute of Technology, National Academy of Sciences of Belarus
Citations	9
Analysis	Full AI Review Included

Technical Analysis and Documentation: Enhanced Corrosion Resistance in Diamond/Aluminum Composites

Executive Summary

This research demonstrates a highly effective method for stabilizing diamond/aluminum (Al) composites—critical materials for high-performance electronic packaging—by utilizing a nanoscale Tungsten (W) coating on the diamond surface. The findings directly support 6CCVD’s expertise in advanced diamond material engineering and custom metalization services.

Core Problem Addressed: The formation of brittle, hygroscopic aluminum carbide (Al₄C₃) at the diamond-Al interface, which leads to severe corrosion and degradation of thermal conductivity (TC) in corrosive environments.
Solution Validation: A 100 nm W coating, applied via magnetron sputtering, successfully inhibited Al₄C₃ formation by preferentially reacting with Al to form Al₁₂W.
Corrosion Resistance Improvement: The W-coated composite exhibited a corrosion rate of only 0.09 mm/a (in 3.5 wt.% NaCl), an improvement of over 92% compared to the uncoated composite (1.21 mm/a).
Stability Enhancement: The W coating significantly improved the stability of thermal conductivity (TC). After full immersion corrosion, the TC of the W-coated composite decreased by only 4.2%, versus a 12.7% decrease for the uncoated material.
Mechanical Performance: Initial bending strength was significantly higher for the W-coated composite (319 MPa) compared to the uncoated composite (222 MPa), demonstrating superior interface bonding.
6CCVD Value Proposition: 6CCVD is uniquely positioned to supply the high-purity Single Crystal Diamond (SCD) precursors and provide the necessary custom nanoscale W metalization required to replicate and scale this interface engineering success for thermal management applications.

Technical Specifications

The following hard data points were extracted from the analysis of W-coated diamond/aluminum composites:

Parameter	Value	Unit	Context
Diamond Particle Size	~100	µm	MBD4-grade synthetic monocrystalline
W Coating Thickness	100	nm	Applied via magnetron sputtering
Sputtering Pressure Range	5 x 10^-3 to 9 x 10^-3	Pa	Constant Ar flow maintained
Sputtering Current / Voltage	0.9 / 600	A / V	Used during W deposition
Composite Preparation Temperature	700	°C	Gas-assisted pressure infiltration
Corrosion Medium	3.5 wt.%	NaCl	Full immersion test environment
Initial Thermal Conductivity (Uncoated)	604	W/(m·K)	Before corrosion treatment
Initial Thermal Conductivity (W-Coated)	579	W/(m·K)	Before corrosion treatment
Corrosion Rate (Uncoated, 24h)	1.21	mm/a	High rate due to Al₄C₃ hydrolysis
Corrosion Rate (W-Coated, 24h)	0.09	mm/a	Significant corrosion inhibition
TC Decrease After Corrosion (Uncoated)	12.7	%	Due to severe interface damage
TC Decrease After Corrosion (W-Coated)	4.2	%	Demonstrates high stability
Initial Bending Strength (W-Coated)	319	MPa	Superior interface bonding
Bending Strength After Corrosion (W-Coated)	195	MPa	Retained mechanical integrity

Key Methodologies

The composite preparation relied on precise surface modification of the diamond particles followed by high-temperature infiltration.

Diamond Precursor Selection: MBD4-grade synthetic monocrystalline diamond particles (~100 µm) were selected as the reinforcement phase.
Nanoscale W Coating: A 100 nm thick tungsten (W) coating was deposited onto the diamond particles using a magnetron sputtering technique (MSP-5100B system).
- Target: Circular W target (Ø 100 mm x 50 mm, 99.99% purity).
- Sputtering Environment: Constant Ar flow maintained sputtering pressure between 5 x 10^-3 Pa and 9 x 10^-3 Pa.
- Parameters: Sputtering current of 0.9 A, voltage of 600 V, and substrate temperature of 400 °C for 180 minutes.
Composite Fabrication: W-coated diamond/aluminum composites (60% diamond volume fraction) were fabricated via gas-assisted pressure infiltration.
- Infiltration Temperature: 700 °C.
- Process: Samples were held at 700 °C for 30 minutes, followed by heating rates of 10 °C/min, and then pressurized until the pressure reached 10 MPa.
Corrosion Testing: Full immersion tests and polarization curve tests were conducted in 3.5 wt.% NaCl solution to evaluate corrosion rate (R) and stability.
Characterization: Phase composition (XRD), microstructure (FE-SEM), mechanical properties (three-point bending), and thermal properties (Netzsch LFA 467 Nanoflash) were measured.

6CCVD Solutions & Capabilities

This research highlights the critical role of precise interface engineering—specifically nanoscale metal coating—in achieving high-performance, stable diamond composites for thermal management. 6CCVD offers the materials and customization services necessary to replicate and advance this technology.

Applicable Materials

The study utilized high-purity synthetic monocrystalline diamond particles. 6CCVD provides the highest quality diamond precursors suitable for advanced composite manufacturing and interface research:

Optical Grade Single Crystal Diamond (SCD): While the paper used particles, 6CCVD can supply high-purity SCD plates/wafers (up to 500 µm thick) that can be precision-diced or processed to serve as high-quality reinforcement components or substrates for R&D into interface reactions.
Polycrystalline Diamond (PCD) Substrates: For large-scale thermal management applications requiring plates up to 125mm in diameter, 6CCVD PCD offers excellent bulk thermal properties and can be customized with surface treatments.

Customization Potential

The success of this research hinged on the precise application of a 100 nm W coating. 6CCVD’s in-house metalization capabilities directly address this requirement:

Research Requirement	6CCVD Customization Capability	Value Proposition
Nanoscale W Coating (100 nm)	Custom Metalization: We offer Tungsten (W) deposition, along with Ti, Pt, Au, Pd, and Cu, with precise thickness control (down to nanometer scale).	Ensures exact replication of the high-stability interface layer (W or Al₁₂W).
Specific Diamond Dimensions (~100 µm)	Precision Laser Cutting & Dicing: 6CCVD can process SCD or PCD wafers into custom shapes and dimensions, ensuring precise component geometry for infiltration processes.	Provides tailored diamond components, not just raw particles, for advanced composite fabrication.
High Purity Requirements	Material Purity: Our MPCVD diamond (SCD and PCD) is grown under highly controlled conditions, ensuring the low defect density necessary for optimal thermal and mechanical performance.	Guarantees the highest quality starting material, minimizing defects that could accelerate corrosion.

Engineering Support

The interface reaction (Al₄C₃ hydrolysis) and subsequent corrosion mechanism are complex challenges in electronic packaging. 6CCVD’s in-house PhD engineering team specializes in diamond interface science and can provide expert consultation for similar projects:

Interface Engineering: Assistance in selecting optimal metal coatings (W, Ti, Cr, etc.) and deposition parameters to suppress detrimental phases like Al₄C₃ and maximize thermal stability.
Thermal Management Applications: Support for engineers developing high-power electronic devices, where maintaining stable thermal conductivity in corrosive or humid environments is critical.
Material Selection: Guidance on choosing between SCD and PCD based on required thermal conductivity, mechanical strength, and cost targets for specific Diamond/Aluminum Composite projects.

Call to Action: For custom specifications or material consultation regarding advanced thermal management composites or interface engineering, visit 6ccvd.com or contact our engineering team directly.

View Original Abstract

The stability of diamond/aluminum composite is of significant importance for its extensive application. In this paper, the interface of diamond/aluminum composite was modified by adding nanoscale W coating on diamond surface. We evaluated the corrosion rate of nanoscale W-coated and uncoated diamond/aluminum composite by a full immersion test and polarization curve test and clarified the corrosion products and corrosion mechanism of the composite. The introduction of W nanoscale coating effectively reduces the corrosion rate of the diamond/aluminum composite. After corrosion, the bending strength and thermal conductivity of the nanoscale W-coated diamond/aluminum composite are considerably higher than those of the uncoated diamond/aluminum composite. The corrosion loss of the material is mainly related to the hydrolysis of the interface product Al4C3, accompanied by the corrosion of the matrix aluminum. Our work provides guidance for improving the life of electronic devices in corrosive environments.

Tech Support

Original Source

DOI: https://doi.org/10.3390/nano13020307

References

2020 - Diamond in medical devices and sensors: An overview of diamond surfaces [Crossref]
2018 - Thermal conductivity of high purity synthetic single crystal diamonds [Crossref]
2014 - Optimisation of high thermal conductivity Al/diamond composites produced by gas pressure infiltration by controlling infiltration temperature and pressure [Crossref]
2021 - Improvement of thermal conductivity of diamond/Al composites by optimization of liquid-solid separation process [Crossref]
2018 - Enhanced thermal conductivity of diamond/aluminum composites through tuning diamond particle dispersion [Crossref]
2020 - Characterization of interfacial bonding strength at Al(Si)/diamond interfaces by neutron diffraction: Effect of diamond surface termination and processing conditions [Crossref]
2016 - Effect of (0-40) wt. % Si addition to Al on the thermal conductivity and thermal expansion of diamond/Al composites by pressure infiltration [Crossref]
2022 - Research progress of diamond/aluminum composite interface design [Crossref]